Up here in New England we get some pretty long cold spells (as in several days in a row below zero F) so this is a real issue for me too. Here is how I plan to tackle it this winter...

Lifeboat Supplies.

The SOLAS approved rations from the better companies like Datrex or Mainstay are designed to be good below freezing. They are low thirst, easy to digest, don't require heating and will keep you alive with plenty of calories for a while.

The water packets from Datrex are reported to be very resilient and are capable of being frozen solid. Avoid the "blox" packaging from other companies (look like juice boxes) and stick with the Datrex 4 oz water packets.

Both the rations and the water have a 5 year shelf life and are made just for this kind of thing.

If you need/want to heat them, remember that the rations and water come in retort packaging so MRE heaters should work great with a bit of water. Or the air-activated chemical warmers (various brands) that you put in your gloves, pockets, et al. can be wrapped around them.

Hope this helps,

MedB